[340] Morphology and Immunophenotype of Ductal Carcinoma In Situ in Triple Negative Breast Cancer

YH Wen, M Akram, T Nehhozina, H Mohammed, L Norton, E Brogi. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Information on precursor lesions associated with triple negative breast carcinoma (TN) is limited. We evaluated the morphology of DCIS adjacent to TN and compared its immunoprofile with that of the coexisting invasive component.
Design: We reviewed cases of TN and identified 54 in which DCIS appeared to be present based on morphology. For each tumor, we selected a representative slide/block with DCIS and performed immunoperoxidase stains for calponin, p63, CK5/6, CK14 and Id4.
Results: All patients were women, with median age 55 y (range 29-84). All TN were invasive ductal carcinoma, including 47 NOS and 5 apocrine; one had medullary features, one was matrix producing. The average tumor size was 2.7 cm (range 0.3-28.0). Forty-one TN (76%) had modified Bloom-Richardson grade 3, 12 (22%) grade 2, and 1 (2%) grade 1. Myoepithelial stains verified DCIS in 41 (76%) cases. Solid nests of invasive carcinoma (10) or lymphovascular invasion (2) mimicked DCIS in 12 cases, a minute focus of DCIS was lost in deeper sections in one case. DCIS was of solid type in 26 (63%) cases, cribriform in 4 (10%) and mixed (solid, cribriform, micropapillary or papillary) in 11 (27%). Nuclear grade was high in 33 (80%) cases, intermediate in 8 (20%). Necrosis was present in 33 DCIS (80%), and was extensive in 11 (27%), moderate in 15 (37%), minimal in 7 (17%). Calcifications in DCIS occurred in 14 (34%) cases. DCIS was positive for basal cytokeratins in 14 (34%) cases: 8 (20%) were CK14+/CK5/6+; 3 (7%) CK14+/CK5/6-; 3 (7%) CK14-/CK5/6+. P63+ cells were seen in 2 DCIS, but only one showed focal positivity for CK14 and CK5/6. Id4, a downregulator of BRCA1 inversely correlated with ER, was detected in 24 of 38 (63%) evaluable DCIS and in all of the adjacent TN. Concordant positive or negative expression in DCIS and adjacent TN was observed for CK14 in 33 (80%) cases, for CK5/6 in 30 (73%) and for Id4 in 36 (95%).

CK14 and/or CK5/614 (34%)19 (46%)
CK14-/CK5/6-27 (66%)22 (54%)
p633 (7%)3 (7%)
Id424 (63%)*28 (68%)
*only 38 DCIS were evaluable

Conclusions: DCIS associated with TN typically has high nuclear grade and necrosis, but carries calcifications in only about a third of cases. When present, DCIS shows basal immunophenotype, similar to that of the adjacent TN, supporting a role as a precursor lesion. Id4 expression in DCIS associated with TN suggests that sporadic BRCA1 inactivation may occur in this type of tumors.
Category: Breast

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 51, Tuesday Morning


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